Roth IRA basis: what it is, why you must track it, and how to rebuild it

What basis means in a Roth IRA

Basis is the part of an account that has already been taxed and therefore cannot be taxed again on the way out. In a traditional IRA it is the unusual case, existing only if you made nondeductible contributions. In a Roth IRA it is the normal case, because no Roth contribution is ever deductible: every dollar you put in arrived after tax, so every dollar you put in is basis.

That gives the answer to what a Roth IRA basis is: the running total of your own already-taxed money in the account. It has exactly two sources.

• Regular contributions — the annual amounts you put in directly, for every year since 1998, net of anything you had returned to you and adjusted for any recharacterizations.
• Conversion and rollover principal — the full amount moved in from a traditional, SEP or SIMPLE IRA, or rolled over from a workplace plan. Not the taxable portion; the whole amount. If you converted $60,000 of pre-tax money and paid tax on all $60,000 that year, your conversion basis went up by $60,000.

Two structural points are easy to miss. First, earnings are not basis. Dividends, interest and capital appreciation inside the account were never taxed, so they are the one layer that can still be taxed on the way out. Second, basis is a single figure across every Roth IRA you own. The tax code aggregates them, so opening a second account does not create a second basis pool — a point that also governs how many accounts are worth holding. And basis is a declining balance: withdrawing it reduces it, permanently.

Contributions, conversions, earnings

Basis is not one undifferentiated pile. It comes out in a fixed order — regular contributions first, then conversions oldest-first, then earnings last — and the layers are taxed and penalised differently. That ordering is the whole subject of the Roth IRA early withdrawal penalty guide, so one paragraph here rather than a repeat of it:

Contribution basis is the friendliest money you own. It comes out tax-free and penalty-free at any age, for any reason, with no waiting period. Conversion basis is also tax-free coming out — you already paid the tax — but each conversion layer carries its own five-year clock for penalty purposes, which is why conversions are tracked separately from contributions rather than lumped in. The mechanics of that clock, and how it differs from the account-level five-year rule, live in the Roth conversion five-year rule guide. Earnings are last in line and the only layer that can produce ordinary income tax.

The practical consequence is that your basis figure is really two figures the IRS asks for separately — contribution basis and conversion basis — which is precisely how Form 8606 lays them out.

When basis matters — and when it stops

Here is the part most explanations bury: basis is irrelevant to a qualified distribution. A qualified Roth distribution is entirely free of income tax, whatever it consists of, so there is nothing to allocate and nothing to prove. Under IRS Publication 590-B, a distribution is qualified when both of these are true: the five-year period beginning with the first year you contributed to any Roth IRA has ended, and the distribution is made after you reach 59½, on account of disability, to a beneficiary after your death, or for a qualified first-time home purchase up to a $10,000 lifetime limit.

Before that point, basis is doing the entire job. It decides how much of a withdrawal is a non-taxable return of your own money and how much is taxable earnings — and, in turn, how much is exposed to the 10% additional tax on early distributions. A 45-year-old with $180,000 in a Roth, of which $96,000 is documented basis, can withdraw up to $96,000 with no income tax and no penalty. The same person with no records is arguing about all of it.

Form 8606 Part III, lines 19–25

Basis is not reported anywhere annually. It surfaces on one form, in one part, and only in a year you take a non-qualified Roth distribution: Part III of Form 8606, "Distributions From Roth, Roth SEP, or Roth SIMPLE IRAs." Read the flow and the logic of the whole subject becomes obvious — it is a subtraction stack, and your basis is what you are subtracting.

Source: Instructions for Form 8606 (Part III, lines 19–25) and Form 8606 itself. Line numbering is stable year to year, but confirm against the instructions for the tax year you are filing.

Notice what the form assumes: that you already know lines 22 and 24. It provides a worksheet for line 22 and a chart for line 24, and both of them point backwards, to your own historical records. The IRS does not supply the number. The form is the place you assert it.

Nobody is tracking this for you

This is the most expensive misunderstanding in the topic, and it is worth stating bluntly: your custodian does not track your Roth IRA basis, and neither does the IRS. Every provider knows what happened at its own firm, in the years you were there. It does not know what you contributed in 2006 at a bank you have since left, which contributions you later recharacterized, or — when you transfer an account in — anything about the basis history behind the assets.

What the custodian does do is file Form 5498 with the IRS each year after the contribution deadline — usually late May, which is why it arrives once you have already filed and gets thrown away. It is the best source of truth for reconstruction:

• Box 10 — Roth IRA contributions for the year.
• Box 3 — Roth IRA conversion amount.
• Box 2 — rollover contributions.
• Box 4 — recharacterized contributions.

Every one of those forms went to the IRS. None of them is cumulative, none of them nets out withdrawals, and no system anywhere adds them up into the figure Form 8606 asks you for. Tracking basis is a taxpayer obligation, discharged with a spreadsheet.

What 1099-R codes J, T and Q actually say

When money leaves, you receive a Form 1099-R — and it will not tell you how much is taxable. For Roth IRA distributions, box 2a (taxable amount) is typically blank with "taxable amount not determined" ticked, because the payer genuinely does not know. Box 7 carries one of three codes, and each is a statement about what the custodian knows, not about your basis.

• Code Q — qualified distribution. The custodian is satisfied the distribution is qualified. Nothing is taxable, Part III of Form 8606 is not required, and your basis is irrelevant.
• Code T — exception applies, five-year period unknown. The custodian knows you are 59½ or older, disabled, or that this is a death distribution, but cannot confirm the five-year clock. The 10% penalty is off the table; whether earnings are taxable depends on a clock only you can evidence.
• Code J — early distribution, no known exception. The default for anyone under 59½. It says nothing about basis: a code-J 1099-R for a $30,000 withdrawal of pure contributions looks identical to one for $30,000 of earnings. Left unaddressed, tax software and the IRS matching system will treat the full amount as income. Form 8606 Part III is how you correct that, and Form 5329 is where you claim any penalty exception.

The same logic applies to the 1099-R you receive for a conversion — the coding conventions there, including why conversions arrive coded 2 or 7 from the distributing IRA, are covered in the Roth conversion 1099-R guide.

How to rebuild a basis you never recorded

Most people arrive at this question late, with twenty years of history and no ledger. Reconstruction is ordinary detective work, and it is far easier now than it will be under examination.

1. Collect every Form 8606 you have ever filed. Line 22 and line 24 of any prior-year Part III give you contribution and conversion basis as of that year. Part II, line 16, of a conversion-year Form 8606 gives the amount you converted that year — the figure the line 24 chart directs you to.
2. Request your Form 5498 history. These are information returns filed with the IRS, so transcripts can be requested for the years still retained (generally around ten). Boxes 10 and 3 rebuild contributions and conversions year by year.
3. Pull January and December statements from each custodian you have used. Contribution activity and transfer-in dates usually show plainly, and year-end values anchor the timeline.
4. Check your own tax returns. Conversions appear as income; a saver's credit claim on Form 8880 evidences a contribution; a recharacterization should have an explanatory statement attached.
5. Sanity-check against the annual limits. You cannot have contributed more than the limit for a given year, or more than your earned income. Where a year is unrecoverable, a conservative estimate capped at the limit and supported by evidence that the account existed is defensible in a way a round number is not.
6. Write the method down alongside the number, and keep the source documents. What you are building is not just a figure; it is the evidence for a figure.

The running basis ledger

The output of all of that is one small table. This is the whole apparatus needed to track a Roth IRA basis — a row per year, two basis columns, and a running total. The example below shows a saver who contributed steadily, converted twice, and took one early withdrawal.

Illustrative only. The 2023 withdrawal of $12,000 comes entirely out of contribution basis under the ordering rules — tax-free and penalty-free — which is why only the contribution column falls. Amounts shown are examples, not the statutory limits for those years.

Three habits make the ledger reliable. Record a contribution in the year it was for, not the year you paid it — money sent in March 2026 for tax year 2025 belongs on the 2025 row. Keep conversions on dated rows of their own, because each has its own five-year clock. And reduce the correct column when you withdraw: a withdrawal consumes contribution basis first, reaching conversion basis only once contribution basis is exhausted.

If you cannot prove your basis

The default position when basis is unsubstantiated is the worst available one. A Roth distribution arrives with a 1099-R showing the gross amount and no taxable figure. If you do not complete Form 8606 Part III and cannot support lines 22 and 24, the amount is treated as fully taxable — and because the undocumented portion is effectively treated as earnings, it can also attract the 10% additional tax on early distributions under §72(t). That is ordinary income tax and a penalty on dollars that were taxed the day you earned them.

Two things soften this. Basis is a question of fact, and reconstructed evidence — 5498 transcripts, statements, contemporaneous records — is how facts are proved; there is no rule that the number must come from a form filed at the time. And the burden only arrives if you take a non-qualified distribution. But the asymmetry is stark: keeping the record costs minutes a year, and not keeping it can cost a marginal-rate tax bill plus 10% on money you never owed tax on. Price the exposure in the withdrawal tax calculator.

Investment risk disclosure: the figures in this article are illustrative arithmetic, not projections. Investments held in a Roth IRA can lose value, past performance does not predict future results, and no rate of return is guaranteed. Tax outcomes depend on your own facts — confirm them with your tax adviser and against the primary sources linked here.

Recharacterizations and 60-day returns

Three transactions move basis in ways that quietly break a ledger, and all three need a row of their own.

• Recharacterization of a contribution. Moving a Roth contribution to a traditional IRA before your filing deadline plus extensions means it is treated as having been made to the traditional IRA all along — so it never becomes Roth basis, and if you already recorded it, remove it. Form 8606's line 22 instructions say explicitly that contribution basis is adjusted for recharacterizations. The reverse direction adds basis. Conversions, note, have not been reversible since 2018; the full mechanics are in the recharacterization guide.
• A returned contribution. Withdrawing an excess or unwanted contribution, with its net income attributable, before the deadline unwinds the contribution entirely. It is excluded from contribution basis — the instructions exclude "contributions that you had returned to you" from line 22 — and the earnings returned with it are taxable in the year of the contribution.
• A 60-day rollover. Taking money out of a Roth IRA and putting it back within 60 days is not a distribution at all, so basis is unchanged. Miss the window, or breach the one-rollover-per-12-months limit, and the withdrawal becomes a real distribution that permanently consumes basis. The deadlines and the once-per-year trap are in the 60-day rollover rule guide.

Rollovers from a designated Roth account in a 401(k) are a fourth case worth flagging: your after-tax deferrals in that plan carry over as Roth IRA contribution basis, and the plan's Form 1099-R box 5 is the figure to record.

The ten-minute annual routine

1. In May, open the Form 5498 instead of filing it in the bin. Reconcile boxes 10 and 3 against what you believe you did.
2. Add one row to the ledger — year, contribution, conversion, withdrawal, running contribution basis, running conversion basis.
3. File Form 8606 whenever it is required, and keep every copy indefinitely. A filed 8606 is the cleanest evidence of basis that exists.
4. Store the ledger where your executor can find it, with the supporting statements. Beneficiaries inherit your basis position and, in a non-qualified year, the same evidentiary problem.
5. Stop when it stops mattering — once you are past 59½ with a five-year-old Roth, keep the file, but the number no longer drives anything.